Conventionally, curable resins including epoxy resins have been widely used in a variety of applications including molding materials, materials for laminated sheet or adhesive agent, various electronic or electric parts, paint and ink materials, and others. In particular, epoxy resin compositions have been used widely as sealants in the applications demanding sealing of electronic parts and elements such as transistor and IC. It is because epoxy resins are well balanced in various properties including moldability, electrical properties, moisture resistance, heat resistance, mechanical properties, adhesion to inserted parts, and others.
On the other hand, in the recent trend toward acceleration and increase in density of electronic parts, heat generation from the electronic devices is becoming more significant. There are also an increasing number of electronic parts that operate at high temperature. Accordingly, there are severe requirements in heat resistance imposed on plastics, in particular epoxy resin hardened products, used in electronic parts.
For improvement in the various properties of epoxy resin hardened product, Japanese Patent Application Laid-Open Nos. 2001-59013 and 2002-249539 disclose methods of using an alkoxy group-containing silane-modified epoxy resin that is obtained by modifying at least part of a hydroxyl group-containing epoxy resin such as bisphenol epoxy resin with an alkoxysilane or the partial condensate thereof as a curing agent. Alternatively, Japanese Patent Application Laid-Open Nos. 2000-281756 and 2001-294639 disclose methods of using an alkoxy group-containing silane-modified phenol resin obtained by modifying part of a phenol resin with an alkoxysilane or the partial condensates thereof as a curing agent.